Calathus and Nebria mating attempt?

Hey everyone,
I raise various Carabids that are found in Oregon and Washington. And in one of my terrariums are a bunch(10+) of Calathus fuscipes, as well as over 20 Nebria brevicollis, and for some reason, several of the male C. fuscipes have been trying to mate with the female N. brevicollis.
I’m not sure if this is possible for them to mate successfully, and I think that it would be pretty cool if they can, but I was wondering if any of you might be able to tell me if it is actually possible for them to mate, and then lay eggs that are hybrids of the two species?

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Hybridization should not be possible.

Successful sperm transfer may or may not be possible.


@coniontises , thanks, this information helps a lot! I do partially hope that it was successful, and that there are hybrids…

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I’ve seen strange mating attempts of beetles in the wild. But i think in a terrarium situation, it may be more likely because the smell of potential mates is everywhere.

@notiophilus Does that mean that the chances of hybridization between two different Genera/species when being kept together in a terrarium is higher? Or do you mean it’s more likely for them to attempt to mate because there are constantly potential mates nearby 24/7?
Either way, thank you for your input on the post!

Hybridisation between genera is almost impossible. There are cases in plants, and i think if its happening it means that the boundaries of the genera are not chosen correctly.

The genetic material of Calathus and Nebria has to be incompatible, as the differences are too big. They are not even closely related genera. Even if they mate, there will be no offspring.

Btw are those two species native to the US? They are common in Europe too.


Nebria brevicollis(Fabricius, 1792) not Native to North America, if link works, see here Nebria brevicollis
As for Calathus fuscipes(Goeze, 1777), I actually do not know if it is introduced or not, but I know that I find them everywhere here in Marion County, OR, USA.
On iNat, it says that C.fuscipes is Native to the US, but I can’t seem to figure out whether it is Native to Europe.

C. fuscipes was described of Europe, and is adventive in North America, according to Bousquet’s Catalogue (2012).

Cheers, G.

Odd, on iNaturalist it show C.fuscipes as being Native, why would it be shown as Native, if it is said differently somewhere else? Which is correct?

Well, you can go to the GBIF page for that species , try the time-lapse chart and see yourself…

Not all of iNat content is “bullet proof”, as it is contributed by very diverse people.

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@gabrif Thank you, I just looked into that, and previously I did not know that it was possible to do anything with the timeline! So, thank you for that as well!

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